You need a better layout for your API documentation. It's a wall of text. Add in a navigation sidebar, or better yet just copy Stripe.
Also the how-tos are too longwinded. You could probably reduce the quantity of prose by 50% or more. e.g. the very first paragraph "Getting logged in is easy and takes only a second..." is waffle and missing a vital opportunity to explain how the damn thing works!
There's an open source project called Slate [1] which is basically a static site generator for API docs you might consider which looks like Stripe's API docs.
Also the how-tos are too longwinded. You could probably reduce the quantity of prose by 50% or more. e.g. the very first paragraph "Getting logged in is easy and takes only a second..." is waffle and missing a vital opportunity to explain how the damn thing works!